JPS6038043Y2 - Control device for two-point ignition engine - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a control device for a two-point ignition engine, and more specifically, to measures against engine noise during high loads.

A two-point ignition engine employs a rapid combustion method in which two spark plugs are installed per cylinder and ignites at the same time, making it possible to reliably burn the air-fuel mixture in the combustion chamber in a short period of time even when a large amount of exhaust gas is recirculated. However, due to the high combustion speed, engine noise is generally large, and noise can become a problem, especially under high loads.

As a countermeasure, a negative pressure switch is used to detect the intake passage negative pressure corresponding to the engine load, and when the intake passage negative pressure is below a set pressure (for example -IQQmmHg) or under high load, one of the spark plugs is activated. by stopping the ignition to achieve one-point ignition, or by shifting the ignition timing of the two spark plugs to delay combustion substantially in the same way as one-point ignition,
Conventionally, efforts have been made to reduce engine noise.

FIG. 1 is a diagram showing a conventional control device for a two-point ignition engine that switches from two-point ignition to one-point ignition at high loads, and FIG. 2 is a diagram showing its operating characteristics.

In Figure 1, 1 is a negative pressure switch, 2 is a series resistor, and 3 is a negative pressure switch.
is the ignition switching circuit, 4 is the distributor, 5a, 5b
are two spark plugs arranged on the intake side and exhaust side of the combustion chamber, 6a and 6b are ignition coils for each spark plug, and the ignition switching circuit 3 switches the exhaust when 12V is applied to its #1 terminal. When the primary side of the side ignition coil 6b is disconnected from the power supply and OV is applied to the #1 terminal, the exhaust side ignition coil 6
The primary side of b is connected to the power supply (12V).

When the intake passage negative pressure is below the set pressure (for example -100mmHg) and the load is high, the negative pressure switch 1 is turned off and 12V is applied from the power supply to the #1 terminal of the ignition switching circuit 3 through the series resistor 2, so that the exhaust side The spark plug 5b becomes inactive, one-point ignition is performed only by the intake side spark plug 5a, and the intake passage negative pressure reaches the set pressure (for example, -100 mmH).
When the load exceeds g), the negative pressure switch 1 is turned on and the #1 terminal of the ignition switching circuit 3 is set to OV, so the intake side spark plug 5a and the exhaust side spark plug 5b operate simultaneously, resulting in two-point ignition. It is done.

In Fig. 2, if 7 is the driving force curve at full load of the engine and 8 is the driving force curve at intake passage negative pressure - 100 mmH, then ■
is the 1-point ignition range, and ■ is the 2-point ignition range.

However, with such conventional control devices for two-point ignition engines, when switching from two-point ignition to essentially one-point ignition, the engine output decreases due to a delay in combustion speed. There were problems with drivability such as shock when switching and hesitation due to insufficient output.

The present invention has been developed in view of the above points, and when switching from two-point ignition to substantially one-point ignition, the air-fuel ratio switching means is simultaneously operated to enrich the air-fuel ratio, so that the ignition is switched. This is intended to compensate for the decrease in output and solve the above problems.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a diagram showing an embodiment of the present invention.

This embodiment is applied to a fuel injection type two-point ignition engine, and the ignition system includes an ignition switching circuit 3, a distributor 4, and two spark plugs 5a and 5 per cylinder, as shown in FIG.
b. It is composed of ignition coils 6a and 6b for each of the ignition coils 6a and 6b, and the ignition switching circuit 3 is configured so that 1-point ignition occurs when 12V is applied to the #1 terminal, and 2-point ignition occurs when QV is applied to the #1 terminal. Performs ignition control.

On the other hand, the fuel system is provided with a fuel injection control unit 7, an injection valve 8, and an air-fuel ratio switching circuit 9.

The fuel injection control unit 7 includes a basic pulse calculation circuit 10,
Consisting of an increase correction circuit 11 and an output amplification circuit 12, it generates an output with increase correction added to the basic pulse width corresponding to engine operating conditions (intake air amount and engine speed), similar to known electronically controlled fuel injection systems. The fuel injection amount is determined by the pulse width.

The air-fuel ratio control circuit 9 includes transistors T1. T2, resistance R1
~R1, surge absorption capacitor C1 protection diode Z
A switching circuit consisting of D, transistors T□, T
2 controls conduction and non-conduction between the #2 terminal (■ power supply terminal) and the #3 terminal (correction input terminal) of the increase correction circuit 11.

The increase correction circuit 11 performs #2. When the #32 terminal is electrically connected, a corresponding fuel increase correction is performed, and when it is not electrically conductive, this fuel increase correction is not performed.

This increase correction function is provided by the same arithmetic circuit as other increase corrections such as increase at start-up.

The negative pressure switch 1 detects the intake passage negative pressure corresponding to the engine load, and when the intake passage negative pressure reaches a set value (for example, -100 mmHg).
), it is turned off at a high load of less than ), and turned on at a low load, where the intake passage negative pressure exceeds a set value (for example, -100 mmHg).

In the above device, at high load when the intake passage negative pressure is below the set value, the negative pressure switch 1 is turned off, so 12V is applied to the #1 terminal of the ignition switching circuit 3, and the ignition system is switched to one-point ignition. Change.

At the same time, the resistors R1 and R2 of the air-fuel ratio switching circuit 9 are also
Since V is applied, transistor T1. T2 is turned on, and #2 of the increase correction circuit 11 is turned on. #3 Bring continuity between both terminals.

As a result, the increase correction circuit 11 operates and switches the air-fuel ratio to approximately the maximum output air-fuel ratio (A/F=13 to 14).

The above-mentioned ignition switching from 2-point ignition to 1-point ignition and the air-fuel ratio switching to increase the amount of fuel are performed simultaneously and instantaneously based on the electrical signal from one negative pressure switch 1. The decrease in engine output is compensated for by enriching the air-fuel ratio, and it is possible to eliminate drivability-related problems such as shocks during switching and hesitation due to insufficient output while the vehicle is running.

When the intake passage negative pressure exceeds the set pressure and the load is low, the negative pressure switch 1 is turned on, so no voltage is applied to the #1 terminal of the ignition switching circuit 3, and the ignition system performs two-point ignition.

Further, since the transistors T□ and T2 of the air-fuel ratio switching circuit 9 are turned off, the increase correction circuit 11 does not operate, and the air-fuel ratio is switched to the lean side.

FIG. 4 is a diagram showing another embodiment of the present invention.

This embodiment is applied to a two-point ignition engine with a carburetor specification, and the configuration of the ignition system is the same as that shown in FIG.
By operating the power valve 14, the amount of fuel is increased so as to enrich the air-fuel ratio.

In order to operate the power valve 14, the solenoid valve 15 is activated at the same time as the negative pressure switch 1 switches the ignition from 2-point ignition to 1-point ignition. The pressure is controlled to atmospheric pressure, and the intake path negative pressure at low loads.

FIG. 5 shows the detailed structure of the air-fuel ratio switching means described above.

In the figure, 17 is a pipe leading to the atmosphere, and 18 is an engine intake pipe (
This is a conduit leading to Figure 5 (25).

When the intake passage negative pressure is below the set pressure and the load is high, the negative pressure switch 1 is turned off, and the ignition switching circuit 3 is activated to switch from 2-point ignition to 1-point ignition, and at the same time, the solenoid valve 15 is also (2) Since 12V20 is applied, the solenoid valve 15 opens as shown in FIG. 5a, and the atmosphere is introduced into the plunger chamber 19.

Therefore, the plunger 16 descends under the force of the spring 20 and pushes open the power valve 14, and the fuel metered by the power jet 22 from the float chamber 21 of the carburetor is added to the fuel metered by the main jet 23, and the fuel is transferred to the main nozzle 24. is supplied to enrich the air-fuel ratio.

When the intake passage negative pressure exceeds the set pressure, the negative pressure switch 1 is turned on, so no voltage is applied to the solenoid valve 15, and the passage 17 leading to the atmosphere is closed as shown in Figure 5.
is closed.

Therefore, the plunger 16 is pulled up by the intake passage negative pressure introduced through the conduit 18, and the operation of the power valve 14 is stopped.

At this time, the ignition switching circuit 3 switches the ignition system to two-point ignition.

Therefore, this embodiment also provides the same effect as the embodiment shown in FIG.

In the above embodiment, one spark plug is inactivated to switch to single-point ignition, but the ignition timing of the two spark plugs may be shifted to delay combustion in the same way as single-point ignition. As the detection means, instead of using a negative pressure switch, the engine load may be detected from the amount of intake air using an air flow meter, throttle opening, or the like.

As explained above, according to the present invention, when the engine has a high load exceeding a set level, the ignition system is switched from two-point ignition to substantially one-point ignition, and at the same time, the air-fuel ratio switching means is activated to enrich the air-fuel ratio. As a noise countermeasure for two-point ignition engines under high load, this structure prevents the reduction in engine output that occurs when switching from two-point ignition to one-point ignition, and prevents shocks and insufficient output when switching while the vehicle is running. Problems related to drivability such as hesitation can be resolved, and engine noise at high loads can be reduced without impairing drivability while taking advantage of the high output, low fuel consumption, and low pollution of a two-point ignition engine. .

[Brief explanation of the drawing]

Figure 1 is a system diagram showing the control device of a conventional two-point ignition engine.
Fig. 2 is a diagram of its operating characteristics, Fig. 3 is a system diagram showing one embodiment of the present invention, Fig. 4 is a system diagram showing another embodiment of the invention, and Fig. 5 is an implementation diagram of the embodiment shown in Fig. 4. It is a detailed diagram of the main part of an example. 1... Negative pressure switch for load detection, 3...
・Ignition switching circuit, 5a, 5b...Spark plug,
7...Fuel injection control unit, 9...
Air-fuel ratio switching circuit, 11... Increase correction circuit, 13
... Carburetor, 14 ... Power valve,
15... Solenoid valve for air-fuel ratio switching.

Claims (3)

[Scope of utility model registration request] (1) In a control device for a two-point ignition engine having two spark plugs per cylinder, a load detection means for detecting a high load state of the engine exceeding a set level, and a load detection means for detecting a high load state of the engine exceeding a set level; The ignition timing of the two spark plugs may be changed from 2-point ignition to substantially 1-point ignition by making them inoperative or by shifting the ignition timing of the two spark plugs.
An ignition switching means for switching to ignition and an air-fuel ratio switching means for increasing the amount of fuel supplied to the engine are provided, and the ignition switching means and the air-fuel ratio switching means are operated simultaneously based on a signal from the operation of the load detection means. 1. A control device for a two-point ignition engine, characterized in that: (2) The two-point ignition engine according to claim 1, wherein the air-fuel ratio switching means comprises a circuit that controls an increase correction circuit of a fuel supply device in conjunction with a negative pressure switch. Control device. (3) The two-point ignition engine according to claim 1, wherein the air-fuel ratio switching means comprises a solenoid valve interlocked with a negative pressure switch and a power valve controlled by the solenoid valve. Control device.